Convexity Preserving Interpolatory Subdivision Schemes

We construct local subdivision schemes that interpolate functional univariate data and that preserve convexity. The resulting limit function of these schemes is continuous and convex for arbitrary convex data. Moreover this class of schemes is restricted to a subdivision scheme that generates a limit function that is convex and continuously differentiable for strictly convex data. The approximation order of this scheme is four. Some generalizations, such as tension control and piecewise convexity preservation, are briefly discussed. November 29, 1996. Date revised: May 28, 1997.     

Molecular basis of LFER: theoretical study of polar substituent effect in aliphatic series

The nature of inductive substituent effect on the gas phase acidity of several series of aliphatic carboxylic acids with rigid molecular skeletons was analyzed using the recently proposed quantum chemical approach based on the theory of proton affinity proposed by Longuet‐Higgins. The results of the analysis suggest that the substituent induced variation of the acidity is in all series due to electrostatic field‐effect which in the gas phase can reasonably be characterized by Kirkwood–Westheimer theory. Copyright © 2007 John Wiley & Sons, Ltd.     

Conversion of trans‐Diboran(4)yl Platinum Complexes into Their cis‐Bisboryl Analogues

The diboran(4)yl trans‐[(iPr₃P)₂Pt(Br){B(NMe₂)B(NMe₂)Br}] ( 1 ) is readily converted into its cis‐bisboryl analogues 2 and 3 by reaction with the chelating bisphosphines 1,2‐bis(dicyclohexylphosphino)ethane (dcpe) and 1,1‐bis(dicyclohexylphosphino)methane (dcpm), respectively. A plausible mechanism of this transformation consists of a sequence of reductive diborane(4) elimination and subsequent reoxidative addition of its B? B bond to the low‐valent platinum centers. Thus, the forced cis configuration of the phosphine ligands induces a change in the preferred reaction site of the diborane(4) with respect to oxidative addition. The reactions proceed with high selectivities, and the cis‐bisboryl complexes 2 and 3 were isolated in moderate yields (55 and 46 %). Moreover, their identity was clearly verified by NMR spectroscopy and X‐ray diffraction studies.     

Improved sample preparation for CE-LIF analysis of plant N-glycans

In view of glycomics studies in plants, it is important to have sensitive tools that allow one to analyze and characterize the N-glycans present on plant proteins in different species. Earlier methods combined plant-based sample preparations with CE-LIF N-glycan analysis but suffered from background contaminations, often resulting in non-reproducible results. This publication describes a reproducible and sensitive protocol for the preparation and analysis of plant N-glycans, based on a combination of the 'in-gel release method' and N-glycan analysis on a multicapillary DNA sequencer. Our protocol makes it possible to analyze plant N-glycans starting from low amounts of plant material with highly reproducible results. The developed protocol was validated for different plant species and plant cells.